Reinforced core bullet

ABSTRACT

A jacketed bullet has a core of a dense metal or metal alloy, an inner jacket at least partially surrounding and bonded to the core; and an outer jacket at least partially surrounding the inner jacket and core.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/083,651, filed Jul. 25, 2008. The disclosure of the above-referenced application is incorporated herein by reference.

FIELD

The present disclosure relates to improvements in bullets, and in particular, to an improved bullet with a reinforced core.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure, and may not constitute prior art.

Considerable effort is devoted to the design of bullets to improve their performance. These efforts include designs to improve mass retention of the bullet after it strikes its target, to maximize the impact of the bullet on the target. These efforts also include designs to improve expansion of the bullet after it strikes its target, to maximize damage to the target. Despite these efforts, improvements are still needed, in particular to maintain bullet performance at higher bullet velocities.

SUMMARY

Generally, embodiments of this invention provide an improved bullet with a reinforced core, and methods of making such bullets. In a preferred embodiment, the bullet comprises a core of a dense metal or metal alloy. An inner jacket at least partially surrounds and is bonded to the core. An outer jacket at least partially surrounds the inner jacket and core.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a longitudinal cross-sectional view of a preferred embodiment of a bullet constructed according to the principles of this invention;

FIG. 2 is photographic longitudinal cross section of a preferred embodiment of a bullet constructed according to the principles of this invention;

FIG. 3 is a photographic perspective view of the reinforced core of the bullet of the preferred embodiment;

FIG. 4 is a photographic perspective view of the outer jacket of the bullet of the preferred embodiment;

FIGS. 5A and 5B are photographic top plan and top perspective views of the manufacture of the bullet of the preferred embodiment, showing the bullet after the nose cavity is formed in the front end;

FIGS. 6A and 6B are photographic top plan and top perspective views of the manufacture of the bullet of the preferred embodiment, showing the bullet after the lines of weakness are formed in the front ends of the jackets;

FIGS. 7A and 7B are photographic top plan and top perspective views of the manufacture of the bullet of the preferred embodiment, showing the bullet after the nose cavity and ogival taper is formed;

FIG. 8 is a photographic rear plan view of an upset of the bullet of the preferred embodiment;

FIG. 9 is a photographic side elevation view of an upset of a bullet of the preferred embodiment;

FIG. 10 is a photographic rear perspective view of an upset of a bullet of the preferred embodiment;

FIG. 11 is a longitudinal cross-sectional view of a pre-formed cup-shaped outer jacket used in an alternate preferred embodiment;

FIG. 12 is a longitudinal cross-sectional view of a pre-formed cup-shaped outer jacket used in an alternate preferred embodiment;

FIG. 13 is a longitudinal cross-sectional view of a pre-formed cup-shaped outer jacket used in an alternate preferred embodiment;

FIG. 14 is a longitudinal cross-sectional photograph of a bullet made according to the alternate preferred embodiment;

FIG. 15A is a photograph of a bullet made according to the preferred embodiment of this invention, after being fired into gelatin at a velocity of 1650 fps; and

FIG. 15B is a photograph of a bullet made according to the alternate preferred embodiment of this invention, after being fired into gelatin at a velocity of 1650 fps.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

A preferred embodiment of a bullet with a reinforced core in accordance with the principles of this invention is indicated generally as 20 in the Figures. Bullet 20 has an ogival tapered nose portion 22 at the front end and a heel 24 at the opposite end. The bullet 20 preferably has a hollow point 26, with a plurality of lines of weakness 28 so that the bullet can expand upon impact with the target, as shown in FIG. 1, the bullet 20 comprises an outer jacket 30 and a reinforced core 32. The reinforced core 32 comprises a relatively soft, dense inner core body 34, and an inner jacket 36.

The inner core body 34 is preferably made of lead or a lead alloy. However, the inner core body 34 could be some other dense metal or material. Because of environmental concerns, for at least some applications, the inner core body 34 can be lead-free, for example comprising tin, tin alloys, tungsten, or tungsten alloys.

The inner jacket 36 is preferably made of copper or a copper alloy. The inner jacket 36 preferably comprises a drawn copper cup 38 in which a pre-formed inner core body 34 is bonded (FIG. 3). In the preferred embodiment, the inner core body 34 and inner jacket 36 are heated to bond them together. The inner core body 34 could alternatively be bonded in the inner jacket 36 with a bonding agent, for example an adhesive such as an epoxy. Alternatively, the inner core body 34 could be cast in the inner jacket 36. In still another alternative, the inner jacket 36 could be applied over the core 26, for example by chemical plating or electroplating.

The outer jacket 30 is preferably made of copper or a copper alloy. The outer jacket 30 is preferably a drawn cup 40 (FIG. 4) into which the reinforced core 24 is inserted and bonded. Forming the outer jacket 30 from a drawn copper or copper alloy cup allows the thickness of the walls of the outer jacket 30 to be varied along the length of the bullet 20. In the preferred embodiment, the portions of the outer jacket 30 adjacent the front 22 of the bullet 20 are thicker than the portions of the outer jacket adjacent the heel 24 of the bullet. The thickness, and the rate of change or taper of the outer jacket 30 can be controlled to adjust the performance of the bullet 22 on impact, for example to change the bullet's performance at a given velocity, or to change the bullet's performance relative to a given barrier (target) type, or to change the degree of expansion upon impact.

The lines of weakness 28 allow the portion of the outer jacket 30 over the front portion 22 of the bullet 20 to expand and form a plurality of petals 42 (FIGS. 8-10). Each of the petals 42 preferably has a bend 44, formed by the portion of the jacket 30 in the hollow of the hollow nose 26, with a point 46 at the end of the petal 42.

The lines of weakness 28 also allow the inner jacket 36 to expand and form a plurality of petals 48, which are generally aligned with the petals 42. Like petals 42, petals 48 each have a bend 50 therein, corresponding to the portion of the jacket at the front 22 of the bullet, and a point 52. Because the inner jacket 36 is bonded to the inner core body 34, the petals 48 pull material from the inner core body 34 with them as they expand. Thus the petals 48 tend not to expand as much as the petals 42, so that their points 52 are offset from the points 46. Furthermore, the petals 48 tend to protect the petals 42, preventing them from expanding too far and/or tearing off.

The bullet 20 is preferably fabricated by inserting a pre-formed inner core body 34 into a pre-formed cup 38 that is the precursor of the inner jacket 36. The inner core body 34 and cup 38 are heated to bond the inner core body 34 in the cup 38, indicated generally as 54 in FIG. 3. The core and cup combination 54 is inserted into a cup 40, which is the precursor of the outer jacket 30 (shown in FIG. 4), with the closed ends of the cups 38 and 40 oriented in the same direction. The walls of the cup 40 preferably have a varying tapered configuration, being generally thicker at the closed end 56 (which forms the front 22 of the bullet 20), and thinner at the open end 58 (which forms the tail 24 of the bullet). The profile of the cup 40 is designed to provide the desired wall thickness for the jacket 30. For example, as shown in FIG. 1, the thickness of the jacket 30 is generally greatest at the front 22 of the bullet 20, and thinnest at the tail 24. More specifically, as shown in FIG. 1, the portion 30 a of the jacket 32 adjacent the bottom of the recess 26 tapers toward the bottom of the recess. The portions 30 b and 30 c at the front end of the bullet on the inside and outside, respectively, of the recess 26 are generally of constant thickness and relatively thick. This thickness allows the bullet to be fired at higher speeds without over expansion. The portion 30 d of the jacket 32 on the side of the bullet tapers toward the heel 28. Finally, the portion 30 e adjacent the heel 24 is relatively thin.

The core and cup combination 54 and the cup 40 are compressed in a die, which simultaneously forms a frustoconical depression 60 in the closed ends of the cups 38 and 40, mechanically bonds the cups and thus, the inner and outer jackets 30 and 36, and wraps the open ends of the cups around the back end of the inner core body 34. The bullet after this operation is shown in FIGS. 5A and 5B. As part of this operation, a disc of copper or copper alloy (or some other metal) can be inserted into the open end of the cup 38 and/or the cup 40, so that as the cups are wrapped around the heel of the bullet, the disc is secured, closing the open end of the bullet.

In the next step, the bullet is pressed in a die to form score lines 62 in the frustoconical depression 60 in the closed ends of the cups 38 and 40, which form the lines of weakness 28 in the outer jacket 30 and the inner jacket 36. The bullet after this operation is shown in FIGS. 6A and 6B. In the preferred embodiment there are six score lines 62 that are equally spaced to form lines of weakness 28 that form petals of equal size. However, there could be fewer or more score lines, and their spacing could be varied to form a different number of petals, and/or petals of more than one size.

In the next step, the bullet is pressed in a die to form the ogival taper in the front 22 end of the bullet. The bullet after this operation is shown in FIGS. 7A and 7B.

The resulting bullet 20 is adapted to be fired at higher speeds, because of the reinforced core 32 (specifically the bonded inner jacket 26), and the thicker outer jacket 30. The outer jacket 30 opens into a plurality of pointed petals 42 that damage the target. The inner jacket 36 similarly opens into petals 48, which because of the bonding with the inner core body 34, pull core material with them. This helps reinforce the petals 42 of the outer jacket, and provides a second set of pointed petals 48. Because of the bonding between the inner core body 34 and the inner jacket 26, the bullet 20 retains substantially all of its weight.

The material from which each of the cups 38 and 40 (and thus each of the jackets 30 and 36) is made, could be the same, but they could be different, to provide different mechanical properties to the bullet 20. The materials can also be different, or treated differently (for example by surface treatment, oxide coating, plating, polishing, etc.) to impart a unique appearance to the bullet (particularly in its upset or fired state). Thus, the colors of the inner jacket 36 and the outer jacket 30 can be different, so that the petals 42 and 48 have different colors, or are otherwise visually different. For example the cup 38 could be made of, or the interior could be plated with, a brass-colored metal alloy, while the cup 40 could be made oft or the interior could be plated with a copper-colored metal alloy. Alternatively, one of the cups could be made oft or plated with, a silver-colored alloy. While it is particularly desirable that the visible surfaces of the petals 42 and 48 (which correspond to the inside of the cups 38 and 40) contrast, the exteriors of the cups 38 and 40 could alternatively or additionally be provided with a contrasting appearance as well.

In an alternate preferred embodiment, at least one of the cup 38 or 40 can formed with at least mechanical retainer to facilitate engagement between the inner and outer jackets 30 and 36. This helps prevent separation of the inner and outer jackets 30 and 367 particularly during high velocity impacts, thereby preserving bullet mass.

Thus in accordance with a first alternate preferred embodiment, an alternative cup 40′ is used, which is provided with a shoulder 64 formed therein. Thus, when the core and cup combination 54 and the cup 40′ are compressed in a die, the shoulder 64 forms a corresponding mating shoulder 66 in the outer surface of the core and cup combination 54. The mating shoulders 64 and 66 help retain the inner jacket and core in the outer jacket when the bullet strikes a target, and the petals on the outer jacket open. Thus, the bullet retains more of its mass.

While the shoulder 64 can be formed perpendicular to the axis of the cup 40′, such as by machining, this would be difficult, time consuming, and expensive. Thus, as shown in FIGS. 11 and 12, the shoulder 64 is preferably a tapering region formed in the sidewall of the cup 40′. The angle of the taper depends upon the construction of the bullet and the speeds at which it will hit a target but the inventors have found that angles as low as 10° can improve retaining the inner jacket 36 in the outer jacket 30. Preferably, the angle of taper is between about 15 and about 20 degrees, which can be conveniently formed as part of the drawings process of making the cup 40′. Of course more than one shoulder can be provided. Thus, in FIG. 13, a cup 40″ having two shoulders 64A and 64B is provided.

The shoulders face away from the front of the bullet, and are preferably spaced sufficiently from the front of the jackets 36 and 30, that they do not interfere with the cuts that for the petals. In the cup 40′ shown in FIG. 11, the shoulder 64 begins about 0.594 inches (about 66.7% of the length) from the closed end of the cup. The shoulder 64 tapers from a diameter of about 0.415 inches to diameter of about 0.3995 inches, at an angle of about 20°. This corresponds to about a 3.9% increase in diameter at the shoulder 64. In the cup 40′ shown in FIG. 12, the shoulder 64 begins about 0.601 inches (about 67.5% of the length) from the closed end of the cup to the front of the cup. The shoulder 64 tapers from a diameter of 0.415 inches at an angle of about 15°. This corresponds to about a 3.9% increase in diameter at the shoulder 64. In the cup 40″ shown in FIG. 13, there are two shoulders 64A and 64B. The shoulder 64A begins about 0.586 inches (about 65.8% of the length) from the closed end of the cup. The shoulder 64A tapers from a diameter of about 0.415 inches to diameter of about 0.3995 inches, at an angle of about 10°. This corresponds to about a 3.9% increase in diameter at the shoulder 64A. The shoulder 64B begins about 0.631 inches (about 70.8% of the length) from the closed end of the cup. The shoulder 64B tapers from a diameter of about 0.425 inches to diameter of about 0.415 inches, at an angle of about 15°. This corresponds to about a 2.4% increase in diameter at the shoulder 64B, and an overall increase of about 6.4% over shoulders 64A and 64B.

The shoulders of this preferred embodiment are preferably spaced about 0.5 to 0.7 inches from the end of the cup. They provide a change in diameter of at least about 2%. The shoulder preferably has an angle of at least about 10°, and more preferably between about 15° and about 20°.

As shown in FIG. 14 the shoulder forms a mechanical interference between the jackets, helping to retain them together. Of course, instead oft or in addition to the shoulder 64 on the inside of the cup 40′ or 40″, a shoulder could be formed on the outside of the cup 38, however it appears that it is more convenient to form the shoulder in the cup 40.

FIGS. 15A and 15B illustrate the difference between a bullet with the shoulder 64, and a bullet without the shoulder 64 when they strike ballistic gelatin at a speed of approximately 1650 fps. The bullet in FIG. 15A separated into two principal parts, but the bullet FIG. 15B did not separate, and thus retained its mass and was more effective for its intended purpose. 

1. A jacketed bullet comprising: a core of a dense metal or metal alloy; an inner jacket at least partially surrounding and bonded to the core; and an outer jacket at least partially surrounding the inner jacket and core.
 2. The jacketed bullet according to claim 1 wherein the inner jacket has a thickness of between about 0.005 inches and 0.02 inches.
 3. The jacketed bullet according to claim 1 wherein the outer jacket is thicker than the inner jacket.
 4. The jacketed bullet according to claim 1 wherein the bond between the core and in the inner jacket is formed by at least partially melting a pre-formed core in a pre-formed inner jacket.
 5. The jacketed bullet according to claim 1 wherein the inner jacket and the outer jacket have longitudinally extending lines of weakness that can separate on impact to form petals.
 6. The jacketed bullet according to claim 1 wherein the lines of weakness in the inner jacket and the outer jacket are aligned, so that the petals formed by the jackets on impact are generally aligned.
 7. The jacketed bullet according to claim 1 wherein the lines of weakness are formed by areas of thinness in the inner and outer jackets.
 8. The jacketed bullet according to claim 1 wherein the lines of weakness are formed by cuts through the inner and outer jackets.
 9. The jacketed bullet according to claim 1 wherein the outer jacket does not upset upon impact in 20% ballistic gelatin at an initial velocity of 1200 fps or less.
 10. The jacketed bullet according to claim 1 wherein the bullet retains at least 99% mass when fired at an initial velocity of 1800 fps or less at 20% ballistic gelatin.
 11. The jacketed bullet according to claim 1 further comprising a mechanical engagement between the inner jacket and the outer jacket.
 12. The jacketed bullet according to claim 11 wherein the mechanical engagement between the inner jacket results from a shoulder preformed in at least one of the outer jacket and the inner jacket.
 13. The jacketed bullet according to claim 12 wherein the mechanical engagement between the inner jacket and the outer jacket results form a shoulder pre-formed in the outer jacket, and a corresponding deformation in the inner jacket.
 14. An improved jacketed bullet of the type comprising a core of a dense metal or metal alloy, and a jacket bonded to the core, the improvement comprising a second jacket disposed over the core and the bonded jacket.
 15. A jacketed bullet comprising: a core of a dense metal or metal alloy; an inner jacket at least partially surrounding and bonded to the core, the inner jacket having generally longitudinally extending lines of weakness therein so that the inner jacket forms petals upon impact; and an outer jacket at least partially surrounding the inner jacket and core, the outer jacket being thicker than the inner jacket, and having lines of weakness therein so that the outer jacket forms petals upon impact.
 16. A method of making a jacketed bullet comprising: bonding a pre-formed core to a pre-formed cup-shaped inner jacket; inserting the core and the inner jacket into a pre-formed cup-shaped outer jacket; and forming a bullet by forming a depression in the closed end of the pre-formed cup-shaped outer jacket; forming the closed end of the pre-formed cup-shaped outer jacket into an ogival front portion of the bullet; and forming a hollow point in the front portion of the bullet.
 17. The method according to claim 16 wherein at least one of the pre-formed cup-shaped inner jacket and pre-formed cup-shaped outer jacket has a shoulder formed therein, and wherein the conforming shoulder is formed in the other of the pre-formed cup-shaped inner jacket and pre-formed cup-shaped outer jacket, as the bullet is formed.
 18. The method according to claim 17 wherein there is a shoulder formed in the pre-formed cup-shaped outer jacket, and wherein the step of forming a bullet forms a corresponding shoulder in the pre-formed cup-shaped inner jacket. 